Tomographic wavefront analysis system and method of mapping an optical system

ABSTRACT

A method of measuring aberrations of a three-dimensional structure of an optical system, such as an eye, includes creating a plurality of light beams, optically imaging the light beams and projecting the light beams onto different locations in an optical system, receiving scattered light from each of the locations, and detecting individual wavefronts of the scattered light. The plurality of light beams may be created and projected simultaneously or sequentially. A system for measuring aberrations of a three-dimensional structure of an optical system includes a light source creating a plurality of light beams, an optical imaging system optically imaging the light beams and projecting the light beams onto different locations in the target optical system, and a wavefront sensor receiving scattered light from each of the locations and detecting individual wavefronts of the scattered light.

BACKGROUND AND SUMMARY OF THE INVENTION

[0001] 1) Field of the Invention

[0002] This invention pertains to the field of measurements ofrefractive errors in an optical system, and more particularly to systemsand methods for compiling a tomographic mapping of the refractive errorsin an optical system such as the eye.

[0003] 2 ) Description of the Related Art

[0004] Measurements of aberrations of the eye are important for thediagnosis of visual defects and acuity. There are a growing number ofways that aberrations can be corrected using both surgical andnon-surgical means. These methods rely on accurate, precise measurementsof the whole ocular system so that patients may be screened, thecorrective means applied and tested, and followed up as appropriate. Inaddition, an enhancement to the accuracy and precision of ocularmeasurements may lead to improved methods for correcting visual defects,and for identifying patients in need of care.

[0005] There are a number of existing methods used to measure theperformance of the ocular optical system. The best established arepsychophysical methods, which rely on subjective patient feedback to forthe parameters of the measurement. The oldest of these is the phoropteror trial lens method. This technique relies on a trial and error methodto identify the required correction. There are psychophysical techniquesfor measuring visual acuity, ocular modulation transfer function,contrast sensitivity and other parameters of interest. Such techniquesare disclosed, for example, in DAVID A. Goss AND ROGER W. WEST,INTRODUCTION TO THE OPTICS OF THE EYE (2002).

[0006] In addition to the subjective methods, there are number ofobjective means for measuring the performance of the ocular system.These include corneal topography, wavefront aberrometry, cornealinterferometry, auto-refraction, and numerous other means for measuringthe eye. These methods may be summarized as described below.

[0007] The surface shape and thickness of the cornea are extremelyimportant information for laser vision correction surgery, inter-ocularcontacts, radial keratotomy, and other surgical repair and correctionschemes. Comeal topography can measure the surface shape of the cornea.Corneal topography can be used to measure the deviation of the cornealshape from the ideal shape required for perfect vision. There areseveral commercial instruments that use different methods to accomplishthis. Many of these methods operate on the cornea directly, and thus itsthickness, shape and other parameters are critical to obtaining goodresults. U.S. Pat. Nos. 4,838,679, 5,062,702, 5,822,035, and 5,920,373to BILLE disclose mapping the cornea of an eye using a variety ofmethods. The cornea has enough of a difference in index of refractionbetween the front and rear surfaces that it is possible to also measurethe corneal thickness.

[0008] However, the cornea only partially contributes to the opticalerrors of the ocular system. Many other elements, such as vitreous fluidand the crystalline lens may also be significant factors that are notaccounted for by corneal topography.

[0009] Another instrument for objectively determining the refraction ofthe eye is the auto-refractor. The auto-refractor uses one of variousmeans to automatically determine the required corrective prescription.This may consist of the projection of one or more spots or patterns ontothe retina. Through adjustment of various optical elements in theauto-refractor instrument, the required correction is automaticallydetected. Numerous auto-refractors have been developed and are in commonclinical use. Examples may be found in U.S. Pat. Nos. 3,819,256 and4,021,102.

[0010] However, the accuracy of the refraction is often suspect, and eyedoctors rarely use this information without further refinement. Thebasic problem with the auto-refractor is that it measures only lowerorder components of the aberrations, such as the spherical andastigmatic errors. Higher order aberrations are not accounted for by theauto-refractor. Only the average performance of the optical system ismeasured by the auto-refractor.

[0011] Recently, there has been attention focused on treatment of theeye as an optical system. This has lead to the application of methodsfor measuring the eye that have previously been used for other opticalsystems, e.g., interferometry, Shack-Hartmann wavefront sensing. Thesetechniques are extremely powerful because they measure the completeaberrations of the eye's optical system.

[0012] In wavefront aberrometry, a spot is projected on the retina ofthe eye and then the resulting scattered light is measured with anoptical system. The full, end-to-end integrated line of sight,measurement of the aberrations of the eye is obtained. Thus, wavefrontaberrometry can be used to measure the full aberration content of theoptical system of the eye from end to end.

[0013] This additional information allows researchers and clinicians tomeasure non-symmetric, non-uniform effects that may be affecting vision.In addition, the information can be linked directly to many of thevarious corrective means to provide greatly improved vision for manypatients.

[0014] U.S. Pat. No. 5,777,719 to WILLIAMS describes the application ofShack-Hartmann wavefront sensing and adaptive optics for determining theocular aberrations to make a super-resolution retina-scope. Thisinformation is then used to make better contact lenses, inter-ocularlenses and other optics as disclosed in U.S. Pat. No. 5,949,521 toWILLIAMS. PCT patent publication WO 00/10448 by AUTONOMOUS TECHNOLOGIESdiscloses refined methods for projecting the light beam onto the retina.U.S. Pat. No. 6,007,204 to ALLYN WELCH discloses a simplified hand heldunit. Commonly owned, co-pending U.S. patent application Ser. No.09/692,483 (Attorney Docket No. WFS.006) to NEAL ET AL. discloses anintegrated instrument that uses an improved projection system tominimize the size of the spot on the back of the eye, and thus allowmuch higher resolution wavefront sensing.

[0015] As described above, corneal topography can be used to measure thedeviation of the corneal shape from the ideal shape required for perfectvision, and wavefront aberrometry can be used to measure the fullaberration content of the optical system from end to end. However, formost surgical (and some non-surgical) procedures, knowledge of both thecorneal shape and the wavefront aberrations is needed. This can beaccomplished by measuring the same eye successively with both awavefront aberrometer and a corneal topographic instrument, or by makingthese measurements with a combined instrument. U.S. Pat. No. 6,050,687to BILLE discloses a method for integrating both corneal topographic andwavefront aberration functions into a single device.

[0016] The objective of such a combined instrument is to identify notonly the aberration content of the eye, but to separate the effects ofthe various contributors. Roughly 30% of the aberration is known to bedue to corneal shape. Thus the remaining 70% is due to other, buriedstructures. Wavefront aberrometry does not provide a measure of thethree-dimensional structure of the index of refraction field. Combiningwavefront aberrometry with corneal topography allows the user todetermine the contribution due to the surface, but does not identify anyother source.

[0017] What is really needed is a means for measuring not only theaberrations of individual structures, but also the fullthree-dimensional structure of an eye or other optical system.

[0018] The measurement of three-dimensional structures interior to amedia is a difficult, if often studied, problem. For human biologicalsystems, a non-invasive procedure is required. This limits the methodsthat are available. Since the eye can be probed only from the front(without extensive surgical methods), there is a natural limit to whatcan be measured. This problem is encountered in x-ray radiology, whereinternal organ or skeletal structure is studied. There are a number oftechniques that have been applied to this field, the most notable ofwhich are nuclear magnetic resonance (NMR) and computed automatedtomography (CAT). These two techniques are eminently successful inmeasuring buried three-dimensional structures in the human body, and areroutinely applied around the world. NMR relies on introducing a magneticmodulation in the molecular and atomic structure of certain elements inthe body, and observing the response. It uses the geometric intersectionof a plane and a line to determine the three-dimensional structure ofthe object under study. Computed automated tomography uses a series ofprojected measurements that are line-integrals through the object understudy to de-convolve the original structure.

[0019] Wavefront sensing is a line-of-sight measurement technique. Theprinciples of computed automated tomography may be applied toreconstruct the three-dimensional structure of an object from multipleviews or measurements of the object obtained by wavefront sensing. Thistechnique has been applied to measure three-dimensional structures in afluid jet. To this end, eight linear wavefront sensors have beenemployed to simultaneously acquire high-speed data. A fullthree-dimensional flow field of the dynamic turbulent jet wasreconstructed using this technique (see L. McMackin, B. Masson, N.Clark, K. Bishop, R. Pierson, and E. Chen, Hartmann Wave Front SensorStudies of Dynamic Organized Structure in Flow Fields, AIAA JOURNAL, 33(11) pp. 2158-2164 (1995)).

[0020] However, many extensions, variations and extrapolations to thesystem and techniques employed for measuring the fluid jet are requiredin order to measure a living eye or other optical system.

[0021] In Liang, et al., Hartmann-Shack Sensor as a Component in ActiveOptical System to Improve the Depth Resolution of the Laser TomographicScanner, SPIE 1542, pp. 543-554 (1991), use of adaptive optics toimprove the resolution of an instrument used to make measurements nearthe retina is reported. A laser tomographic scanner is used to measurethe retina. However, the wavefront sensor and adaptive optics system ofLiang, et al. is only employed to improve the resolution of the scanner.

[0022] Accordingly, it would be advantageous to provide a system capableof measuring not only the aberrations of the individual structures, butalso the full three-dimensional structure of the eye or other opticalsystem. It would also be advantageous to provide a method of measuringthe aberrations of the full three-dimensional structure of the eye orother optical system. Other and further objects and advantages willappear hereinafter.

[0023] The present invention comprises a method and system forperforming optical system measurements that overcome at least one of theabove disadvantages.

[0024] It is an object of this invention to determine the threedimensional structure of the eye or other optical system. This may berealized by projecting multiple spots onto a retina in such a mannerthat the wavefront aberration resulting from each spot may be separatelydetermined, either simultaneously or sequentially. This group ofwavefront aberration maps may then be analyzed using the methods ofcomputed automated tomography to determine the three dimensionalstructure of the eye or other optical system. These and other objects ofthe present invention will become more readily apparent from thedetailed description given hereinafter.

[0025] In one aspect of the invention, a tomographic wavefront analysissystem comprises a projection system creating a plurality of collimatedlight beams; an optical imaging system receiving the plurality ofcollimated light beams and simultaneously providing the plurality ofcollimated light beams onto a plurality of different locations in aneye; and a wavefront sensor simultaneously receiving scattered lightfrom each of the different locations.

[0026] In another aspect of the invention, a method of measuringaberrations of a three-dimensional structure of an optical systemincludes creating a plurality of collimated light beams, simultaneouslyproviding the plurality of collimated light beams onto a plurality ofdifferent locations in the optical system, and simultaneously receivingscattered light from each of the different locations.

[0027] In yet another aspect of the invention, a tomographic wavefrontanalysis system comprises a projection system creating a light beam andscanning the light beam in a plurality of desired directions, an opticalimaging system receiving the scanned light beam and providing thescanned light beam onto a plurality of different locations in an eye,and a wavefront sensor receiving scattered light from each of thedifferent locations.

[0028] In still another aspect of the invention, a method of measuringaberrations of a three-dimensional structure of an optical systemincludes creating a light beam and scanning the light beam in aplurality of desired directions, providing the scanned light beam onto aplurality of different locations in an optical system, and receivingscattered light from each of the different locations.

[0029] In a further aspect of the system, a wavefront sensor for awavefront analysis system, comprises a lenslet array receiving andfocusing scattered light and a plurality of detector arrays located atdifferent detector planes for detecting the focused scattered light fromthe lenslet array, wherein each of the detector arrays is color-coded tosubstantially detect only light corresponding to a differentcorresponding wavelength.

[0030] In a still further aspect of the invention, a lenslet arrayreceiving and focusing scattered light and a detector array having amosaic pattern of color-coded pixels detecting the focusedscattered-light.

[0031] In yet another aspect of the invention, a corneal topographymeasurement can be incorporated along with the tomographic wavefrontanalysis system. The corneal topographer can be any of several designs,the placido disc system being the representative type of that system.The mathematical reduction of the data uses data from placido discs orthe light emitting diodes or other arrangement to determine the surfaceshape of the cornea. Then the tomographic wavefront analysis system isused to mathematically determine the internal three dimensionalstructures of the eye.

[0032] However, it should be understood that the detailed descriptionand specific examples, while indicating the preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1A shows a tomographic wavefront analysis system;

[0034]FIG. 1B shows a plurality of light spots being projected onto theretina of an eye;

[0035]FIG. 2 shows a detailed construction of a wavefront sensor;

[0036]FIG. 3 shows an embodiment of a sequential-measurement tomographicwavefront analysis system;

[0037]FIG. 4 shows an embodiment of a simultaneous-measurementtomographic wavefront analysis system;

[0038] FIGS. 5A-5D illustrate relevant portions of a system and methodfor simultaneously analyzing wavefronts measured at different angles ofanalysis;

[0039]FIG. 6 shows a system for spectrally separating focal spots to beprojected onto an eye and detecting these spots with a color wavefrontsensor;

[0040]FIG. 7 shows an alternative embodiment of a sequential-measurementtomographic wavefront analysis system; and

[0041] FIGS. 8A-D show four different wavefront maps from the same eyethat have been measured and analyzed with an ophthalmic wavefrontanalysis system;

[0042]FIG. 9 shows a method for measuring the eye at different angles bychanging a target fixation point.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Embodiments and other aspects of the invention described herein,including the system embodiments described below, may be made or used inconjunction with inventions described, in whole or in part, inco-pending U.S. patent application Ser. No. 09/692,483 filed on Oct. 20,2000 in the name of inventors Daniel R. Neal, Darrell J. Armstrong,James K. Gruetzner, and Richard J. Copland entitled “DYNAMIC RANGEEXTENSION TECHNIQUES FOR A WAVEFRONT SENSOR INCLUDING USE IN OPHTHALMICMEASUREMENT”(hereinafter “the WFS.006 Application”) which is herebyincorporated herein by reference for all purposes as if fully set forthherein.

[0044]FIG. 1A shows a generalized diagram of one embodiment for atomographic wavefront analysis system 100. In general, the tomographicwavefront analysis system 100 includes: a projection system 110comprising a light source 112, a collimating lens 114, an aperture 115,and a polarizing beam splitter 116; an optical imaging system 120comprising lenses 122 and 124, aperture 125, and quarter wave plate 126;and a wavefront sensor 130 including a lenslet array 134 and a sensor(e.g., a detector array 136). The tomographic wavefront analysis system100 also includes a data analysis system 150 including a processor 152.

[0045] The tomographic wavefront analysis system 100 measuresaberrations of the optical elements that make up the eye. It projectslight into the eye, pre-compensates this light for the eye's dominantaberrations, and then measures reflected and scattered light from theretina with the wavefront sensor 130 which may be, e.g., aShack-Hartmann wavefront sensor.

[0046] Significantly, according to the present invention, thetomographic wavefront analysis system 100 is adapted to perform acombination of multiple off-axis wavefront measurements to obtain agreater depth of information than is possible from a single (typicallyon-axis) measurement. To this end, light is projected on the retina ofthe eye at several different locations or positions. The resultant lightspots should be arranged so that one or more of the spots are off-axisfrom the line of sight determined, for example, by patient alignmentwith a visual target. The wavefronts produced by imaging theseindividual light spots through the eye and the optical system aremeasured independently, giving several separate wavefront sensormeasurements of the eye. This information may be processed using themethods of computed automated tomography to determine the threedimensional structure of the region where all the light paths intersect.

[0047] As noted above, the tomographic wavefront analysis system 100projects light onto the retina with an optical imaging system 120 thatpre-compensates for the eye's stronger defocus and astigmaticaberrations. This increases the resolution that may be used by thewavefront sensor 130. In this configuration, it is necessary to minimizestray reflections. This may be accomplished by off-axis injection withan internal spatial filter, by the use of polarization components, or byother methods. An optical system that can inject light into the eye at asignificant angle may be used. The greater the angle, the better thespatial-resolution of the measurement near the pupil. This maynecessitate the use of higher numerical aperture optics than those usedfor direct ocular aberrometry.

[0048] It is also important to maintain the proper image distance, sothat an image of the pupil is relayed to the lenslet array 134 orsensing plane of the detector array 136. With this image conjugaterelationship, all of the light will be incident on the lenslet array 134and a direct mapping may be obtained between ocular pupil andmeasurement plane. However, the light from each of the different spotsthat have been projected onto the retina will arrive from differentangles at the wavefront sensor 130. Thus by the focal plane of thewavefront sensor 130, depending upon the sensor design, the spots willoccupy completely different groups of pixels in the detector array 136.This can be used to separate the different measurements, as will bediscussed in more detail below.

[0049] In operation, as shown in FIG. 1B, an eye 2 is arranged so thatits cornea 8 or pupil is conjugate to the lenslet array 134.Significantly, the projection system 110 is adapted to project a patternof light spots onto the eye 2 at various positions 4, 6, etc., includingmultiple off-axis positions. The light spots may be projectedsimultaneously, or a pattern of spots may be sequentially createdthrough scanning or controlling the light, as will be described in moredetail below. Light scattered from these different focal spots 4, 6traverses the crystalline lens and cornea 8 from different directions.This scattered light is collected by the optical system 120 and isanalyzed by the wavefront sensor 130. While a Shack-Hartmann wavefrontsensor has been shown by example, a shearing interferometer, Moiré,Hartmann or any other sensor that measures the wavefront of light can beused. The imaging system lenses 122, 124 can be adjusted to compensatefor net defocus error of the eye so as to minimize the dynamic rangerequired by the wavefront sensor 130.

[0050] In an alternative embodiment, improved resolution of structuresin the eye may be obtained by varying the image distance. This can bedone by leaving the eye stationary and moving the location of thewavefront sensor 130 along the optical axis. This will cause theconjugate plane of the lenslet array 134 to change to be in front of orbehind the pupil of the eye. The data gathered can then be converted tothree-dimensional structures of the eye by the techniques of computedautomated tomography. This may be used alone or in combination withother techniques disclosed herein.

[0051]FIG. 2 shows a more detailed view of an embodiment of a wavefrontsensor 200 that may be used in the tomographic wavefront analysis system100. FIG. 2 shows how an incoming wavefront 232 is dissected by thelenslet array 234 to create a pattern of focal spots 238 that aredetected by sensor 230. The resulting information is stored in aprocessor for analysis. The lenslet array 234 will create separateimages on the detector array 236 for each “direction of analysis”. Thereare a variety of ways to separate these images and determine theresulting wavefront.

[0052] Separating the various wavefront measurements so that the datacan be interpreted properly is a key requirement of a system and methodof measuring the aberrations of the full three-dimensional structure ofthe eye with a tomographic wavefront analysis system. Approaches tomeeting this requirement can be divided into two general categories: (1)sequential systems/methods, and (2) simultaneous systems/methods. Eachof these methods has different advantages and disadvantages.

[0053] With the simultaneous methods, it is possible to make temporallyresolved measurements. This prevents an error from being generated inthe measurement resulting from any movement of the eye, or changes inthe medium or alignment, between measurements. However, the need forseparating the various simultaneously produced images can result in alower overall dynamic range for the system. In addition, a relativelyfixed number of angular measurements are possible.

[0054] On the other hand, with sequential measurement methods, it ispossible to utilize the full dynamic range of the wavefront sensor foreach measurement. In addition, the number of points to be analyzed canbe completely arbitrary. However, the light scanning system addscomplexity (e.g., moving parts in some cases) and may be subject tochanges in the medium or alignment between measurements, especially ifthe eye moves significantly during the measurements.

[0055] Sequential and simultaneous systems and methods, and preferredembodiments thereof, will hereafter be discussed in more detail.

[0056] Sequential Systems & Methods.

[0057] When sequential measurement is employed, light ray bundles arriveat an intermediate focal plane as separated bundles of light. This planeis conjugate to the spots projected on the retina. A mask placed at thisintermediate plane can be used to separate and discriminate the variousmeasurements. The mask can consist of a pattern of transparent regionsor holes arranged in an appropriate pattern. The data can be acquiredsequentially by allowing only light to pass through the desired hole.This can be controlled using one of several means. In one embodiment, alight valve, such as a liquid crystal device or other light modulationdevice with the appropriate pattern, is inserted at the focal plane.This light valve is sequentially operated with the proper timing to letlight through at the appropriate point in the measurement sequence.Alternatively, a disk with an appropriate pattern of holes can beinserted at the intermediate focal plane. This disk is adjusted so thatonly one hole allows light through in any given position.

[0058]FIG. 3 illustrates relevant portions of a sequential-measurementtomographic wavefront analysis system 300 that includes a scanning lightprojection system 310. The system 300 also includes an optical imagingsystem 320, a wavefront sensor 330, and a data analysis system 350including a processor 352 in similarity to FIG. 1.

[0059] In the system 300, a lens 314 collimates light from a lightsource 312 (e.g., a laser diode or super-luminescent-diode (SLD)). Thecollimated light is polarized through a polarizing beam splitter 316. Atan image plane that, through the optical imaging system 320, isconjugate the corneal plane, a scanning mirror 318 is used to direct theinjected light beam to desired locations as a function of time.Alternatively, the scanning mirror 318 may be placed at different pointsin the optical imaging system 320 as required, with appropriate opticsto image it to the correct conjugate plane. This scanning mirror 318 isdynamically adjusted to project focal spots at a number of differentangles over a predetermined time period. With modem scanning mirrors, avery rapid set of measurements can be obtained. The measurements aresynchronized to the acquisition of the wavefront sensor 330. Forexample, thirty measurements can readily be obtained in one second evenusing low cost, off-the-shelf cameras in the wavefront sensor 336.

[0060]FIG. 3, an aperture plate 328 is placed at the intermediate focalplane conjugate to the spots projected on the retina. The number ofapertures in the plate 328 limits the number of different angles thatcan be acquired. Thus, even though the scan mirror 318 could bepositioned arbitrarily to a large number of candidate positions, inpractice the number of measurements is limited by the construction ofthe intermediate aperture plate 328. One solution to this problem hasbeen mentioned earlier whereby the aperture plate 328 is replaced by aprogrammable element such as a light valve (e.g., a liquid crystaldevice) or other type of movable or variable aperture. While thisincreases the flexibility of the angular measurements, it also increasesthe complexity of the system.

[0061]FIG. 7 is an alternative embodiment that avoids these problemswithout significant increase in complexity. In this case, a second relaytelescope 742, 744 is added between the scanning mirror 760 and the eye2 to facilitate acquisition of a larger number of angular measurements.Since there is no aperture plate at the intermediate plane for thissecond telescope 742, 744, there is no limitation on the number of scanpositions. This also has the advantage that all of the pre-correctioncomponents 720 are independent from the scan components 740. Thissimplifies the construction of the instrument by separating thefunctions. The range-limiting aperture is still used at position 725,but consists of a single fixed aperture.

[0062] A detailed description of this embodiment is as follows. Theprojection system 710 includes a single light source 712 (which may be alaser diode, light emitting diode, or super-luminescent diode)collimated with a lens 715 and filtered with an aperture 715. The lightfrom the projection system 710 is injected through polarizer 718 intothe polarizing beam splitting cube 716. The polarizing beam splittingcube 716 reflects the s-polarized light into the optical system 720,which comprises the lenses 722 and 724 and the range-limiting aperture725. The lenses 722 and 724 may be moved relative to one another topre-correct both the injected and return light for the focus aberrationsof the eye 2. The light is incident on the scan mirror 760, which islocated at the image plane of optical system 740 conjugate to the eye 2.The scan mirror 760 is adjusted dynamically to inject and receive thelight from many different angles from the eye. Since there are noapertures between the injection lenses 742 and 744, the scan mirror 760can be used to sample a large number of points. This can be accomplishedthrough synchronizing the scan mirror 760 to the camera acquisition. Inaddition, it may be desirable to use a pulsed light source 712 so thatdiscrete locations of the signal may be recorded. The quarter wave plate746 converts the linearly polarized light into circularly polarizedlight before injection into the eye 2. After scattering from the retinasurface, the light is collected by the crystalline lens 9 and the cornea8 and imaging system 740. This light will have orthogonal polarizationto the injected beam. It will also return in a path parallel andcollinear with the injected beam. The scan mirror 760 will thenre-orient this light to be exactly aligned with the optical axis of thewavefront sensor 730, where it will be collected by optical system 720and re-imaged onto the wavefront sensor 730. In this configuration, thewavefront sensor 730 always receives nearly collimated light that iswell aligned with the optical system, since all the light that isincident on the lenslet array 734 must have passed through the rangelimiting aperture 725, and thus can not be deviated by more than thedynamic range of the wavefront sensor 730. The position of the scanmirror 760 for each measurement angle is recorded and used to determinethe angle of the measurement. This is used in the data analysis by dataanalysis system 750 including a processor 752, to determine the internalstructure of the eye.

[0063] Simultaneous Systems & Methods.

[0064] To simultaneously record the various required images, some formof angle-dependent encoding is needed. Each focal spot on the back ofthe eye must be encoded with information regarding its location. Thiscan be done in several ways.

[0065] In one embodiment, position encoding may be employed. In thatcase, a wavefront sensor that spatially separates the light from thevarious fields at widely different angles is employed. In oneembodiment, the wavefront sensor includes a lenslet array that is“smaller” than the detector array. Such encoding may be performed usinga camera (e.g. a KODAK Megapixel or SMD 1M15), with having more totalpixels than the number of lenses in the lenslet array, so that eachlenslet would map onto a larger number of pixels. Thus, the measurementsdo not overlap, allowing simultaneous acquisition. This allows thesub-areas-of-interest needed for position encoding.

[0066] Alternatively, wavelength encoding is employed. By simultaneouslyprojecting a slightly different color of light onto each location of theeye being measured, each spot is “color-coded”. In this case, a colorwavefront sensor is employed for straightforward decoding of the signal.Accordingly, the various spots are allowed to overlap from the differentfields.

[0067]FIG. 4 illustrates relevant portions of a simultaneous-measurementtomographic wavefront analysis system 400 that includes a lightprojection system 410 for simultaneously projecting a pattern of focalspots onto the retina of the eye. The system 400 also includes anoptical imaging system 420, a wavefront sensor 430, a data analysissystem 450 including a processor 452 that are each functionally similarto the corresponding components shown in FIG. 1.

[0068] In the system 400, a number of point light sources 412 areprovided by, for example an array of SLDs, light emitting diodes (LEDs),or even holes in a back illuminated plate (also shown in FIG. 5C). Thelight sources 412 are imaged through a single lens 414 and an aperturegrid 415. The lens 414 transforms the linear position differences of thelight sources 412 into a set of collimated beams at different angles.The optical imaging system 420 is used to image the different lightbeams at different angles to different spots on the retina of the eye.

[0069] FIGS. 5A-5C illustrate relevant portions of a system and methodfor simultaneously analyzing wavefronts measured at different angles ofanalysis. In this configuration a number of spots are simultaneouslyprojected onto the retina at different positions using a system andmethod, e.g. the system 400 shown in FIG. 4 above. FIG. 5A shows thepattern of focal spots on the detector array 536. In this pattern, thereis a central spot 554 and one or more off-axis spots 556. These focalspots are spatially isolated due to the differences in theangle-of-arrival. FIG. 5D shows a detailed cross-section view of alenslet array 534 for a Shack-Hartmann wavefront sensor 530, where lightfrom all of the different views are incident upon the lenslet array 534and thus focused onto a detector array 536. The differentangles-of-arrival result in spatially separated spots 544 and 546. Byassigning each of these spots to its own Area Of Interest (AOI) 552, thecentroid location can be determined within the AOI. A reference set ofwavefronts can be recorded with the same system to establish thelocation of these AOIs and to establish the appropriate mapping. Withthis arrangement, it is convenient to analyze up to nine focal spots perlenslet as shown in FIG. 5B. In this case the lenslet aperture 562 isarranged with the focal spots on the boundary and corners. Each focalspot 560 has the same size AOI 564. Adjacent lenslets have a similarpattern. This type of system may require the use of a large formatcamera to achieve the same resolution obtainable from a single focalspot. FIG. 5C shows how an array of SLDs or LEDs 570 can be used tocreate a plurality of beams at different angles. This is accomplished bycollimating the emitted light with the lens 572 and limiting the beamsize with the aperture 574.

[0070]FIG. 6 illustrates a system and method for spectrally coding thefocal spots projected onto the retina and spectrally separating thescattered light received back from the focal spots. To this end, each ofthe focal spots is coded by using light of a slightly differentwavelength, λ. This coding can be achieved with an angular-tuned filter626, or by using different color SLDs or LEDs. A three-color CCD camera640, for example, is used to spectrally separate the images onto threeseparate CCD detector planes 645, 646 and 647. This allows high dynamicrange, high-resolution wavefront measurements to be made with a simpleoptical system. However, such a system and method is limited in practiceto examining a few, e.g., three angles.

[0071] With a pair of continuously variable filters, it is possible toexamine a much wider frequency range. Using LCD technology, it ispossible to build electrically controlled optical filters. A fixedpattern of different color focal spots is projected onto the eye, andthe images sequentially recorded with different settings of theelectronic filter. This has the advantage of no moving parts, butrequires sequential acquisition of the data, similar to the scanningsystems discussed above.

[0072] The details of a spectral separation system and method will nowbe presented in more detail. An angularly tuned filter 626 can beconstructed using the principle of narrow band interference coatings.The filter can be either reflective or transmissive, depending upon thedesign of the coatings. A filter of this type will exhibit theproperties described in FIG. 6. In this case, varying the angle of thefilter will vary the wavelength of light that it transmits or reflects.By choosing a nominal design point 614 with the filter 626 at a tiltedposition, the wavelength can be adjusted both up 611 and down 615 fromthe center wavelength 613 at the corresponding angles. Thus, abroad-band source 622 (at least broader than the spread in wavelengthsλ₁ 611 to λ₂ 615), can be used in combination with the filter 626 tocreate light that is coded angularly with wavelength according to 620.In this case, a large LED 622 is approximately collimated with lens 624.The large area of the source 622 leads to a range of angles aftercollimation through the lens 624. After passing through the filter 626described previously, the light at a given angle will be coded bywavelength. Thus is provided a means for associating light at aparticular angle with a particular wavelength.

[0073] This light source 620 can then be used, instead of the source412, in conjunction with the tomographic wavefront sensor 400 forsimultaneous recording and detection of the wavefront at different probeangles through the optical system. After passing through the opticalsystem 420, the eye 2, and returning to the wavefront sensor 430, thelight from the different angles will be incident on the lenslet array434 and create focal spots on the detector array 436. These spots may,in general, overlap. The spots are detected and separated by use of thecolor wavefront sensor 630 or 640.

[0074] In one embodiment, the color wavefront sensor 630 consists of amosaic focal plane detector with color filters arranged over the variouspixels. A refractive lenslet array 632 is used in front of the detectormosaic 636 to create the focal spots in a manner that is not dependentupon the wavelength of the incident light. Since the mosaic of detectorelements 636 includes samples at multiple different colors, reading onlythose pixels that have a coding for a particular wavelength (e. g. “B”)will result in reading out the information pertaining only to theparticular color (e.g. “B”), even though spots created by a differentcolor incident light are also present and may even overlap. This methodof recording the position of focal spots that are spectrally coded isvery simple and robust, but is limited to a few colors in order tomaximize the resolution of the spot decimation and position finding.Commercial mosaic focal plane arrays are available that have red, greenand blue coatings (RGB) and are in common use as color imaging sensors.However, for the tomographic wavefront sensor 100, it may be more usefulto build a special color wavefront sensor 630 with a different spectralrange. For example the pixels labeled RGB may consist of filters with850, 830 and 810 nm respectively.

[0075] An alternative embodiment for the color wavefront sensor is the3-CCD camera system shown in 640. In this embodiment, the lenslet array641 creates focal spots at intermediate image plane 642. These spots mayoverlap, but are the result of the color coding scheme 620 and are thusspectrally separate. The relay imaging lens 644 is used to relay theimage of the intermediate image plane to detector planes 645, 646, and647. At each of these planes a detector array (e.g. a CCD array) islocated. The spectral filters 648 and 649 are used to spectrally isolatethe wavelengths that can be transmitted to each of the respectivedetector planes. Thus the full image of the focal spot pattern at theintermediate image plate 642 is present at each detector plane 645, 646and 647, but spectrally isolated according to the desired color-coding.

[0076] Color 3-CCD imaging sensors are available commercially withspectral coatings for red, green and blue wavelengths. For use in thetomographic wavefront analysis system 100, a different set of filtersmay be chosen with wavelengths appropriate for the eye measurement (e.g.850, 830 and 810 nm).

[0077] A larger number of wavelengths may be used to provide more thanthree angular samples with the tomographic wavefront analysis system100. These may be arranged in combination with the spatial separationtechniques 400 to create a larger grid of measurement angles. Forexample, if three colors (e.g. 850, 830 and 810 nm) are spectrallyisolated, then a pattern arranged in both the x-direction andy-direction can be arranged by using a pair of filters 626 arranged inorthogonal directions. This will allow up to nine different angles to besampled while allowing the spots to overlap somewhat and takingadvantage of all other features of the invention.

[0078] Other arrangements are possible, and may be readily identified bythose skilled in the art.

[0079] For example, as described above, the primary requirement of thetomographic wavefront sensor system is the ability to make measurementsof the optical system, e.g. the eye, at different angles. While FIGS.1-7 depict different arrangements for objectively and mechanicallymaking simultaneous or sequential measurements of the optical wavefrontaberration from different angle measurements, it is also possible toacquire these measurements by moving the object under test. For the caseof the human eye this can be accomplished by using an instrument similarto that described in the WFS.006 Application, with the exception of achange in the target. As depicted in FIG. 9. The instrument in theWFS.006 Application includes an internal target system 940 that is usedfor patient fixation and to control patient accommodation. To makemeasurements of the eye at different angles, the target 942 in thetarget system 940 can be changed to force the eye to focus on differentpositions. Instead of focusing only on an axis that is directly alignedwith the optical system of the measuring instrument, the target can bearranged with a number of off-axis locations. This can be achievedeither by physically moving the target 942, or by providing anelectronic or other means for repositioning the apparent position of thetarget center. As an example, a grid of light emitting diodes that couldbe individually controlled could be used as a target. In this case theindividual LED corresponding to the desired measurement would beilluminated, then the corresponding wavefront recorded, then the nextLED corresponding to the next desired measurement location illuminated,and so on successively until all the desired measurements have beenmade. This provides the same measurements, with a similar number ofdifferent angular positions as the other methods described above.However, while simple, this method has the disadvantage that theseparate measurements are made at times that are widely separated. Thusthe average performance of the eye under test would be measured. This,in many cases, is adequate.

[0080] Data Analysis.

[0081] An objective of the previously described methods and systems wasto develop a set of measurement data of the optical system from a numberof different angles. With the measurements being performedsimultaneously, or nearly simultaneously, the measured data can be usedtogether to determine many of the details of the internal opticalsystem. This is what is called tomographic reconstruction. As shown inFIG. 1, the data gathered by the wavefront sensor 130 is provided to adata analysis system 150 including a processor 152 and memory. Asdescribed in more detail below, the data analysis system 150 performs atomographic reconstruction of the optical system (e.g., the eye) byprocessing the measured data according to one or more aspects of theinvention.

[0082] An example of measuring the same optical system at severaldifferent angles is shown in FIGS. 8A-D.

[0083]FIG. 8A-D show four different wavefront maps from the same eyethat have been measured and analyzed with the ophthalmic wavefrontanalysis system described in the WFS.006 Application. In FIG. 8a, theon-axis aberrations are shown. FIGS. 8B-D are off-axis measurements ofthe same eye, where the measurements were acquired with the eyeapproximately 15 degrees left, 15 degrees up and 15 degrees down,successively. The low order aberrations were removed from wavefrontsthat are presented in FIGS. 8A-D for clarity. It is clear from examiningthese images that the angular position of the eye has a big influence onthe resulting aberrations. By combining the information contained in anumber of such measurements the internal structure can be determined.

[0084] In a classic tomographic reconstruction, such as in a computerautomated tomography (CAT) scan or magnetic resonance imaging (MRI)procedure, a number of data sets are acquired from many different anglesthrough the system. In this case, the 3D structure being measured isconstructed from a number of different discrete measurements. Fouriertransform techniques can then be used to reconstruct the internalstructure. This can also be used in the tomographic wavefront sensor. Inthis case the wavefront can be sampled at the resolution of the lensletarray (or interpolated if appropriate to provide higher resolution), andthen the different fields can be fed into the tomographic reconstructionalgorithm.

[0085] An alternative method can also be used for optical systems, suchas the eye, where some knowledge of the internal structure is known inadvance (“a-priori”). The eye, for example, has several external andinternal surfaces where there are differences in the index ofrefraction. These include the cornea anterior and posterior surface, theanterior chamber, the crystalline lens (posterior and anterior surface)the vitreous and the retina. While the exact location, separation,curvature, and shape of these various elements is not known, there are afairly limited number of elements that are needed to describe theinternal structure.

[0086] The internal structure of the lens in the eye is known to have anindex of refraction that varies with the radial position from the centerof the lens and this radial dependence may also be measured by thetomographic analysis.

[0087] Since Zernike polynomials are commonly used to describe thewavefront, it is natural to use these same polynomials to describe theshape of the various internal components. However, these are convenientmathematical constructs only, and any other set of polynomials ormathematical descriptors can be used.

[0088] The various surfaces are described in terms of the following: ScaAnterior Surface of the cornea Scp Posterior surface of cornea tcCorneal center thickness tac Anterior chamber center thickness SlaAnterior surface of the crystalline lens Slp Posterior surface of thecrystalline lens tl Crystalline lens center thickness

[0089] The various surfaces can also be described in terms of a fewadditional constants. These include the radius of curvature, conicconstant and coefficients that represent small deviations from theseshapes. For example, the surfaces can be represented by:${S\left( {x,y} \right)} = {\frac{{C_{x}x^{2}} + {C_{y}y^{2}}}{1 + \sqrt{1 - {\left( {1 + k_{x}} \right)\left( {C_{x}^{2}x^{2}} \right)} - {\left( {1 + k_{y}} \right)\left( {C_{y}^{2}y^{2}} \right)}}} + {\sum\limits_{k = 6}^{N}{a_{k}{Z_{k}\left( {x,y} \right)}}}}$

[0090] where:

[0091] C_(x) and C_(y) are constants defining the radius of curvaturesin the x and y directions;

[0092] k_(x) and k_(y) are conic constants in the x and y directions;

[0093] Z_(k) define a set of polynomials; and

[0094] a_(k) are polynomial coefficients.

[0095] This description of the surfaces includes a general anarnorphicconic surface shape and arbitrary deviation from the pure conic shape.To the fourth order, this surface requires 13 parameters to becompletely described. Each of the four surfaces, Sca, Scp, Sla and Slpcan be expanded in this way. In addition, each of these surfaces mayhave principle axes that are rotated relative to the reference frame,yielding an additional parameter for each surface. Thus each surface (tothe fourth order) would need 14 parameters. Including the various centerthicknesses, this yields a total of 60 parameters to completely describethe eye, including the internal structure. These parameters mayconveniently be collected into a single list, b_(k), where k=(1, 60).Knowledge of these parameters would give the total transmitted wavefronterror, the corneal surface curvature, shape and thickness, the internallens shape, thickness and wavefront error. The data can be analyzed frommany different standpoints. For example, the combined on-axis cornealtopography and wavefront measurement can be readily generated. A cornealthickness map (pachymmetry) or cornea surface curvature can be readilydetermined from the data. In short, this provides all of the informationneeded for complete analysis of the eye for diagnosis, pathology,surgery planning and many other applications.

[0096] Each of the measurements at the various angles providesinformation about the rays that are collected through that particularangle. These describe the best-fit expansion of the wavefront in termsof Zernike or other polynomials. However, for a high-resolutioninstrument (see, e.g., the WFS.006 Application) this may be the resultof fitting over 800 individual slope measurements to the data. Giventhat it may be desirable to probe the ocular system from a number ofdifferent angles (3 to 25), there are a very large number of individualmeasurements that can be used to determine the internal structure. Thesystem is significantly over-determined.

[0097] The analysis proceeds by forming a metric, which describes thenet optical path difference (OPD) between the parameterized surface andthe measured data. Thus, for each angle that is probed by thetomographic wavefront system α, the net OPD is determined by a ray tracethrough the optical system with the parameters that describe thesurfaces b_(k) consisting of a list of the previous surface parameters.This is compared to the measured optical path difference (OPD_(m)) forthat angle, and summed over all angles and all points in each field:$\chi^{2} = {\sum\limits_{a}{\sum\limits_{x,y}\left\lbrack {{{OPD}\left( {b_{k},\alpha,x,y} \right)} - {{OPD}_{m,\alpha}\left( {x,y} \right)}} \right\rbrack^{2}}}$

[0098] This now allows a normal least-squares solution for theparameters b_(k) through minimization of _(X) ² with respect to theparameters b_(k). A number of methods exist for this solution, includingGauss-Seidel solution, singular value decomposition or iterativeleast-squares. If some of these surfaces are known from othermeasurements, such as a corneal topography measurement (e.g., Sca andScp are known), then this information can be used to improve theaccuracy of determining the other parameters.

[0099] The advantage of this type of technique over the Fouriertransform tomographic reconstruction methods is that the resolution ofthe Shack-Hartmann wavefront sensor is inherently dissimilar in thespatial directions (x, y) versus the ordinal direction (z). The lensletarray (or pixel size for other wavefront measurement methods) determinesthe spatial resolution, whereas the wavefront resolution (the minimumwavefront that can be accurately determined) is determined by detectorand lenslet characteristics, algorithms and other effects. Typically thespatial resolution may be 200-300 μm, whereas the wavefront resolutionmay be less than 0.1 μm. Thus the Fourier transform method, whileapplicable to this application, may yield results that are at thelenslet resolution (200-300μm). This may not be adequate for someapplications.

[0100] The least-squares fit method should result in measurements thatare accurate to the sub-micron level except where the various angles donot overlap. This non-overlapping region is conveniently handled by thepolynomial representation, since it includes the best definition for thevarious surfaces even for regions of only partial overlap.

[0101] When a person focuses their eyes at different distances, theinternal shape of the lens inside the eye changes while the otherstructures in the eye change very little. In one embodiment, a target isincorporated that is presented at different distances for the patient tofocus on. Then the tomographic measurement is done with the eye focusedat different distances. The mathematical algorithms are adjusted to keepsome of the parameters of the three-dimensional structure fixed, whileallowing the shape and thickness of the lens to vary to best fit themeasured data. This technique allows for increased resolution in themeasurement of the structures in the eye.

[0102] In some cases, symmetry or other mathematical effect may limitthe accuracy of the terms that can be derived. For structures that arefar removed from the pupil of the optical system, the overlap of thevarious probe angles may be reduced. Thus the full aberrations may havea limited pupil over which they can be determined. These limitationsdepend upon the details of the particular embodiment and are notlimitations of the invention itself.

[0103] While preferred embodiments are disclosed herein, many variationsare possible which remain within the concept and scope of the invention.Such variations would become clear to one of ordinary skill in the artafter inspection of the specification, drawings and claims herein. Theinvention therefore is not to be restricted except within the spirit andscope of the appended claims.

What is claimed is:
 1. A tomographic wavefront analysis system,comprising: a projection system projecting a plurality of light beams,the projection system comprising, a light source simultaneouslyproducing a plurality of light beams, a collimating lens collimating theplurality of light beams, an aperture grid passing therethrough theplurality of collimated light beams; a polarizing beam splitterreceiving and polarizing the plurality of collimated light beams; and anoptical imaging system receiving the polarized collimated light beamsand simultaneously providing the polarized collimated light beams onto aplurality of different locations in an eye; and a wavefront sensorsimultaneously receiving scattered light from each of the locations, thewavefront sensor including a lenslet array, receiving and focusing thescattered light, and a detector array detecting the focused scatteredlight.
 2. The system of claim 1, wherein the optical imaging systemcomprises: a pair of lenses disposed in an optical path between thescanning mirror and the eye; and a quarterwave plated disposed in anoptical path between the pair of lenses and the eye.
 3. The system ofclaim 1, wherein the light source produces a plurality of light beamseach having substantially a same wavelength.
 4. The system of claim 3,wherein the lenslet array comprises a first number of lenslets and thedetector array comprises a second number of pixels, and wherein thesecond number is substantially greater than the first number.
 5. Thesystem of claim 1, wherein the light source produces a plurality oflight beams each having a corresponding different wavelength.
 6. Thesystem of claim 5, wherein the detector array comprises a mosaic patternof color-coded pixels, each color-coded pixel substantially detectingonly light corresponding to one of the different wavelengths.
 7. Thesystem of claim 5, wherein the wavefront sensor further comprises secondand third detector arrays, each of the detector arrays being color-codedto substantially detect only light corresponding to one of the differentwavelengths.
 8. The system of claim 7, wherein the wavefront sensorfurther comprises at least one spectral filter disposed in an opticalpath between the lenslet array and the detector arrays, the spectralfilter spectrally filtering the focused scattered light provided to thedetector arrays.
 9. The system of claim 1, further comprising aprocessor receiving data from the detector array and determiningtherefrom a set of parameters describing surfaces of structures internalto the eye.
 10. A tomographic wavefront analysis system, comprising: aprojection system projecting a scanned, polarized, collimated lightbeam, the projection system comprising, a light source producing a lightbeam, a collimating lens collimating the light beam, an aperture gridpassing therethrough the collimated light beam; a polarizing beamsplitter receiving and polarizing the collimated light beam, a scanningmirror reflecting and scanning the light beam over a plurality ofdesired directions as a function of time; and an optical imaging systemreceiving the scanned, polarized, collimated light beam and directingthe scanned polarized collimated light beam onto a plurality ofdifferent locations in an eye; and a wavefront sensor receivingscattered light from each of the locations, the wavefront sensorincluding a lenslet array, receiving and focusing the scattered light,and a detector array detecting the focused scattered light.
 11. Thesystem of claim 10, further comprising a light valve disposed in anoptical path between the eye and the wavefront sensor, the light valvesequentially passing the scattered light to the wavefront sensor. 12.The system of claim 11, where the light valve is disposed at anintermediate focal plane conjugate to the locations in the eye where thelight is scattered.
 13. The system of claim 11, wherein the light valvecomprises a liquid crystal device.
 14. The system of claim 10, furthercomprising a disk disposed in an optical path between the eye and thewavefront sensor, the disk having a pattern of holes therein selectivelypassing the scattered light to the wavefront sensor.
 15. The system ofclaim 10, wherein the optical imaging system comprises: a pair of lensesdisposed in an optical path between the scanning mirror and the eye; anda quarterwave plated disposed in an optical path between the pair oflenses and the eye.
 16. The system of claim 10, further comprising arelay telescope disposed in an optical path between the light source andthe scanning mirror, the relay telescope comprising first and secondlenses and a plate with an aperture therein disposed between the firstand second lenses.
 17. The system of claim 16, wherein the opticalimaging system consists of: a pair of lenses disposed in an optical pathbetween the scanning mirror and the eye; and a quarterwave plateddisposed in an optical path between the pair of lenses and the eye. 18.The system of claim 10, wherein the scanning mirror is synchronized withdetector array.
 19. The system of claim 10, further comprising aprocessor receiving data from the detector array and determiningtherefrom a set of parameters describing surfaces of structures internalto the eye.
 20. A tomographic wavefront analysis system, comprising: aprojection system creating a plurality of collimated light beams; anoptical imaging system receiving the plurality of collimated light beamsand simultaneously providing the plurality of collimated light beamsonto a plurality of different locations in an eye; and a wavefrontsensor simultaneously receiving scattered light from each of thedifferent locations.
 21. The system of claim 20, wherein the opticalimaging system comprises: a pair of lenses disposed in an optical pathbetween the projection system and the eye; and a quarterwave plateddisposed in an optical path between the pair of lenses and the eye. 22.The system of claim 20, wherein the projection system produces aplurality of light beams each having substantially a same wavelength.23. The system of claim 22, wherein the wavefront sensor comprises: alenslet array having a first number of lenslets receiving and focusingthe scattered light; and a detector array having a second number ofpixels detecting the focused scattered light, wherein the second numberis substantially greater than the first number.
 24. The system of claim20, wherein the proj ection system produces a plurality of light beamseach having a corresponding different wavelength.
 25. The system ofclaim 24, wherein the wavefront sensor comprises: a lenslet arrayreceiving and focusing the scattered light; and a detector array havinga mosaic pattern of color-coded pixels detecting the focused scatteredlight, wherein each color-coded pixel substantially detects only lightcorresponding to one of the different wavelengths.
 26. The system ofclaim 24, wherein the wavefront sensor comprises a plurality of detectorarrays, each of the detector arrays being color-coded to substantiallydetect only light corresponding to one of the different wavelengths. 27.The system of claim 26, wherein the wavefront sensor further comprisesat least one spectral filter disposed in an optical path between thelenslet array and the detector arrays, the spectral filter spectrallyfiltering the focused scattered light provided to the detector arrays.28. The system of claim 20, further comprising a processor receivingdata from the wavefront sensor and determining therefrom a set ofparameters describing surfaces of structures internal to the eye.
 29. Amethod of measuring aberrations of a three-dimensional structure of atarget optical system, comprising: creating a plurality of collimatedlight beams; simultaneously providing the plurality of collimated lightbeams onto a plurality of different locations in the target opticalsystem; and simultaneously receiving scattered light from each of thedifferent locations.
 30. The method of claim 29, wherein creating aplurality of collimated light beams comprises creating a plurality ofcollimated light beams each having substantially a same wavelength. 31.The method of claim 29, wherein creating a plurality of collimated lightbeams comprises creating a plurality of collimated light beams eachhaving a corresponding different wavelength.
 32. The method of claim 29,further comprising: detecting wavefront data from the scattered light;and processing the detected wavefront data to determine therefrom a setof parameters describing surfaces of structures internal to the targetoptical system.
 33. The method of claim 32, wherein processing thedetected wavefront data to determine therefrom a set of parametersdescribing surfaces of structures internal to the target optical systemincludes using a priori information regarding the internal structuresincrease an accuracy of the determined set of parameters.
 34. The methodof claim 29, wherein the target optical system is an eye, and furthercomprising: performing a corneal topography measurement of the eye;detecting wavefront data from the scattered light; and processing thedetected wavefront data to determine therefrom a set of parametersdescribing surfaces of internal structures of the eye, whereinprocessing the detected wavefront data includes using corneal surfaceparameters from the corneal topography measurement to increase anaccuracy of the determined set of parameters.
 35. A tomographicwavefront analysis system, comprising: a projection system creating alight beam and scanning the light beam in a plurality of desireddirections; an optical imaging system receiving the scanned light beamand providing the scanned light beam onto a plurality of differentlocations in a target optical system; and a wavefront sensor receivingscattered light from each of the different locations.
 36. The system ofclaim 35, wherein the projection system includes a scanning mirror andscanning the light beam in a plurality of desired directions.
 37. Thesystem of claim 35, further comprising a light valve disposed in anoptical path between the target optical system and the wavefront sensor,the light valve sequentially passing the scattered light to thewavefront sensor.
 38. The system of claim 37, wherein the light valvecomprises a liquid crystal device.
 39. The system of claim 35, furthercomprising a disk disposed in an optical path between the target opticalsystem and the wavefront sensor, the disk having a pattern of holestherein, the disk selectively passing the scattered light to thewavefront sensor.
 40. The system of claim 35, further comprising a relaytelescope disposed in an optical path between the projection system andthe optical imaging system, the relay telescope comprising first andsecond lenses and a plate with an aperture therein disposed between thefirst and second lenses.
 41. The system of claim 40, wherein the opticalimaging system consists of: a pair of lenses disposed in an optical pathbetween the scanning mirror and the target optical system; and aquarterwave plated disposed in an optical path between the pair oflenses and the target optical system.
 42. The system of claim 35,further comprising a processor receiving data from the wavefront sensorand producing therefrom a set of parameters describing surfaces ofstructures internal to the target optical system.
 43. A method ofmeasuring aberrations of a three-dimensional structure of a targetoptical system, comprising: creating a light beam; scanning the lightbeam in a plurality of desired directions; providing the scanned lightbeam onto a plurality of different locations in the target opticalsystem; and receiving scattered light from each of the differentlocations.
 44. The method of claim 43, further comprising: detectingwavefront data from the scattered light; and processing the detectedwavefront data to determine therefrom a set of parameters describingsurfaces of structures internal to the target optical system.
 45. Themethod of claim 44, wherein processing the detected wavefront data todetermine therefrom a set of parameters describing surfaces ofstructures internal to the target optical system includes using a prioriinformation regarding the internal structures increase an accuracy ofthe determined set of parameters.
 46. The method of claim 43, whereinthe target optical system is an eye, and further comprising: performinga corneal topography measurement of the eye; detecting wavefront datafrom the scattered light; and processing the detected wavefront data todetermine therefrom a set of parameters describing surfaces of internalstructures of the eye, wherein processing the detected wavefront dataincludes using corneal surface parameters from the corneal topographymeasurement to increase an accuracy of the determined set of parameters.47. A tomographic wavefront analysis system for measuring a targetoptical system, comprising: means for creating a plurality of lightbeams; means for optically imaging the light beams and projecting thelight beams onto a plurality of different locations in the targetoptical system; and means for receiving scattered light from each of thelocations and detecting individual wavefronts of the scattered light.48. The system of claim 47, wherein the means for optically imaging thelight beams and projecting the light beams onto a plurality of differentlocations in the target optical system comprises means forsimultaneously imaging the light beams and projecting the light beamsonto a plurality of different locations in the target optical system.49. The system of claim 48, wherein the means for creating a pluralityof light beams comprises means for producing the plurality of lightbeams having substantially a same wavelength.
 50. The system of claim50, wherein the means for producing the plurality of light beams havingsubstantially a same wavelength comprises a plurality of laser diodes.51. The system of claim 49, wherein the means for receiving scatteredlight from each of the locations and detecting individual wavefronts ofthe scattered light includes means for spatially separating the receivedscattered light.
 52. The system of claim 51, wherein the means forreceiving scattered light from each of the locations and detectingindividual wavefronts of the scattered light includes: a lenslet arrayhaving a first number of lenslets receiving and focusing the scatteredlight; and a detector array having a second number of pixels detectingthe focused scattered light, wherein the second number is substantiallygreater than the first number.
 53. The system of claim 48, wherein themeans for creating a plurality of light beams comprises means forproducing the plurality of light beams each having a correspondingdifferent wavelength.
 54. The system of claim 53, wherein the means forproducing the plurality of light beams each having a correspondingdifferent wavelength comprises: a broadband light source creating lighthaving a plurality of wavelengths; an angularly tuned filter receivingthe light and producing therefrom the plurality of light beams eachhaving a corresponding different wavelength, each said light beam beingprojected at a different angle from the angularly tuned filter.
 55. Thesystem of claim 53, the means for receiving scattered light from each ofthe locations and detecting individual wavefronts of the scattered lightincludes means for spectrally separating the received scattered light.56. The system of claim 55, wherein the means for receiving scatteredlight from each of the locations and detecting individual wavefronts ofthe scattered light includes: a lenslet array receiving and focusing thescattered light; and a detector array having a mosaic pattern ofcolor-coded pixels detecting the focused scattered light, wherein eachcolor-coded pixel substantially detects only light corresponding to oneof the different wavelengths.
 57. The system of claim 55, wherein thewavefront sensor comprises a plurality of detector arrays, each of thedetector arrays being color-coded to substantially detect only lightcorresponding to one of the different wavelengths.
 58. The system ofclaim 47, wherein the means for optically imaging the light beams andprojecting the light beams onto a plurality of different locations inthe target optical system comprises means for sequentially imaging thelight beams and projecting the light beams onto a plurality of differentlocations in the target optical system.
 59. The system of claim 58,wherein the means for creating a plurality of light beams comprises ascanning mirror.
 60. The system of claim 58, further comprising a lightvalve disposed in an optical path between the target optical system andthe means for receiving scattered light from each of the locations anddetecting individual wavefronts of the scattered light, the light valvesequentially passing the scattered light to the means for receivingscattered light from each of the locations and detecting individualwavefronts of the scattered light.
 61. The system of claim 47, furthercomprising means for receiving detected wavefront data and determiningtherefrom a set of parameters describing surfaces of structures internalto the target optical system.
 62. A wavefront sensor for a wavefrontanalysis system, comprising: a lenslet array receiving and focusingscattered light; and a plurality of detector arrays located at differentdetector planes and detecting the focused scattered light from thelenslet array, wherein each of the detector arrays is color-coded tosubstantially detect only light corresponding to a differentcorresponding wavelength.
 63. The wavefront sensor of claim 62, furthercomprising at least one spectral filter disposed in an optical pathbetween the lenslet array and the detector arrays, the spectral filterspectrally filtering the focused scattered light provided to thedetector arrays.
 64. A wavefront sensor for a wavefront analysis system,comprising: a lenslet array receiving and focusing scattered light; anda detector array having a mosaic pattern of color-coded pixels detectingthe focused scattered light.
 65. A tomographic wavefront analysissystem, comprising: a projection system creating a light beam; afixation target sequentially focusing the eye in a plurality ofdifferent directions; an optical imaging system receiving the light beamand providing the light beam sequentially onto a plurality of differentlocations on a retina of the eye corresponding to the differentdirections in which the eye is focused by the fixation target; and awavefront sensor receiving scattered light from each of the differentlocations.
 66. The system of claim 65, further comprising a processorreceiving data from the wavefront sensor and producing therefrom a setof parameters describing surfaces of structures internal to the eye. 67.A method of measuring aberrations of a three-dimensional structure of aneye, comprising: creating a light beam; sequentially focusing the eye ina plurality of different directions providing the light beamsequentially onto a plurality of different locations on a retina of theeye corresponding to the different directions in which the eye isfocused by the fixation target; and receiving scattered light from eachof the different locations.
 68. The method of claim 67, furthercomprising: detecting wavefront data from the scattered light; andprocessing the detected wavefront data to determine therefrom a set ofparameters describing surfaces of structures internal to the eye. 69.The method of claim 68, wherein processing the detected wavefront datato determine therefrom a set of parameters describing surfaces ofstructures internal to eye includes using a priori information regardingthe internal structures increase an accuracy of the determined set ofparameters.
 70. The method of claim 67, further comprising: performing acorneal topography measurement of the eye; detecting wavefront data fromthe scattered light; and processing the detected wavefront data todetermine therefrom a set of parameters describing surfaces of internalstructures of the eye, wherein processing the detected wavefront dataincludes using corneal surface parameters from the corneal topographymeasurement to increase an accuracy of the determined set of parameters.